Patent GB-957005-A (GB)
Title: Water-resistant adhesives
Inventor: SHEERAN NORMAN JAMES
IPC: C09J103/02
Filed: 1962-04-16
Abstract: A heat-settable aqueous alkaline adhesive composition comprises starch and a starch-reactive alkali-soluble coniferous tree bark derivative obtained by solvent extraction using hot water or hot or cold aqueous ammonia as solvent, the bark derivative being present in an amount effective to impart water-resistance to the adhesive when set by heat and the adhesive having a total solids content of 15 to 30% by weight. The bark derivative may be a partially sodium substituted product when extraction is done with ammonia. Specified starches are maize, tapioca, sago, potato and pearl. The alkalies specified are sodium, hydroxide and carbonate and calcium hydroxide. Specified trees are Douglas fir, Western hemlock, Sitka spruce and Southern yellow pine. The derivatives are thought to be complex mixtures of tannins, sugars, ash-producing inorganic compounds and dihydroquercetin. The composition may contain formaldehyde, furfuraldehyde, paraformaldehyde and glyoxal alone or with resorcinol and/or urea which form reaction products therewith, and borax.  The preparation of the adhesive may comprise forming an ungelatinised starch slurry by heating a mixture of starch and water, mixing said slurry with a viscous carrier and mixing with either the slurry or carrier the tree bark derivative in dry or solution form. Other components may be added to carrier, slurry or mixture of carrier and slurry. The viscous carrier may be carboxymethyl-cellulose, artificial or natural gums or an aqueous gelatinised starch slurry formed by heating a mixture of starch, water and alkali and then cooling.ALSO:A heat-settable aqueous alkaline adhesive composition comprises starch and a starch-reactive alkali-soluble coniferous tree bark derivative obtained by solvent extraction using hot water or hot or cold aqueous ammonia as solvent, the bark derivative being present in an amount effective to impart water-resistance to the adhesive when set by heat and the adhesive having a total solids content of 15 to 30% by weight.  The bark derivative may be a partially sodium substituted product when extraction is done with ammonia.  Specified starches are maize, tapioca, sago, potato and pearl.  The alkalies specified are sodium hydroxide and carbonate and calcium hydroxide. Specified trees are Douglas fir, Western hemlock, Sitka spruce and Southern yellow pine. The derivatives are thought to be complex mixtures of tannins, sugars, ash-producing inorganic compounds and dihydroquercetin. The composition may contain formaldehyde, furfuraldehyde, paraformaldehyde and glyoxal alone or with resorcinol and/or urea which form reaction products therewith, and borax.  The preparation of the adhesive may comprise forming an ungelatinized starch slurry by heating a mixture of starch and water, mixing said slurry with a viscous carrier and mixing with either the slurry or carrier the tree bark derivative in dry or solution form.  Other components may be added to carrier, slurry or mixture of carrier and slurry.  The viscous carrier may be carboxymethyl-cellulose, artificial or natural gums or an aqueous gelatinized starch slurry formed by heating a mixture of starch, water and alkali and then cooling.ALSO:The layers in corrugated paperboard, wood to wood laminates and paper to wood laminates are bonded together by a heat-settable, aqueous alkaline adhesive composition comprising starch and a starch-reactive coniferous tree bark derivative obtained by solvent extraction using hot water or hot or cold aqueous ammonia as solvent, the bark derivative being present in an amount effective to impart water-resistance to the adhesive when set by heat and the adhesive having a total solids content of 15 to 30% by weight. Specified starches are maize, tapioca, sago, potato and pearl. Specified trees are Douglas fir, Western hemlock, Sitka spruce and Southern Yellow pine.  The composition may contain formaldehyde, furfuraldehyde, paraformaldehyde and glyoxal alone or with resorcinol and/or urea which form reaction products therewith, and borax.  In the examples, corrugated paperboards are prepared by applying adhesive to a fluted board, placing thereon a flat liner and then pressing the structure with heated plates.